Around for less than two decades, exchange-traded funds (ETFs) have made quite a splash in the sea of investment choices.

These bundles of stocks, or bonds, or currencies or whatever-instruments-you-can-lump-together have seen their popularity rise because they trade like stocks do so investors can buy and sell them all day long if they choose. Plus, their expenses are relatively low. Sans commissions, of course.

According to the Investment Company Institute (ICI), the trade association for the mutual fund industry and ETF data, in August there was $656 billion invested in all types of ETFs. Of the 735 different exchanged-traded funds around, the category names they fall under include domestic equity, (it includes both domestic broad-based and domestic sector/industy ETF data), global international equity, hybrid and bond ETFs.

As you might guess, the largest numbers of ETFs are those that fall under the domestic equity heading (430 or them do). ICI lists only 6 hybrid ETFs.

A recent piece in The Wall Street Journal (http://tinyurl.com/yelgeth) pointed out that assets invested in ETFs represent only about 5 percent of those in mutual funds. I would have thought it were more given the number of investment advisors I know who love these vehicles and pitch them like crazy to their clients.

Knowing what an ETF is and how it might be a wise investment choice for you, however, takes education.

Back to that WJS story, in it the author listed a number of ETF Web resource sites and thought I’d pass the info on in case you missed reading it. They include:

A Google search for ETFs will also yield a host of other sites with educational data and information, most of them brought to you from the makers of these investment products, like iShares and Vanguard.

However you slice it, these products are here to stay, work well for some, not others, and need to be understood before ever investing one penny in.